In a principal aspect, this invention relates to sediment flushing apparatus in a water heater tank.
In a typical residential water heater having a cylindrical tank, the water to be heated is introduced into the lower portion of the tank through an inlet conduit and withdrawn from the upper portion of the tank through an outlet. Due to naturally occurring properties of the water, sediment and/or hard water scale may collect in the bottom of the tank.
Hard water scale collects in water heater tanks because its solubility decreases as the water temperature increases. Thus, cold inlet water includes, minerals in solution, such as calcium carbonate, etc. that precipitate from the water as it is heated and collect as sediment at the bottom of the water heater tank. As the sediment collects and coats the bottom of the tank, it impeded the heat transfer capabilities of the tank, thereby reducing the thermal efficiency of the water heater. Thus, it is desirable to remove the sediment from the water heater tank to maintain the efficiency of the water heater.
The most familiar method of removing sediment from the bottom of a water heater tank is to periodically drain a portion of the contents of the tank. To this end, water heater tanks are generally provided with drain valves at their lower end. Historically, sediment has been removed from the water heater tank through the drain valve by merely opening the drain valve and permitting the natural movement of water as the tank empties to sweep the sediment out of the tank. A problem associated with this method is that the velocity of the water caused by the natural draining movement is insufficient to sweep all of the sediment out of the bottom of the water heater tank. Therefore, a portion of the sediment fails to be dislodged or removed from the bottom of the tank. Particularly, larger aggregations of sediment remain in the bottom of the water heater tank and are not swept away by the water's natural movement during such draining. Consequently, to achieve acceptable heat transfer characteristics, the tank must be drained relatively frequently.
Another method of removing sediment that collects in the bottom of a water heater tank is to divert the influent water along the bottom of the tank so as to agitate the sediment whenever influent water is entering the tank. This is usually accomplished by decreasing the cross section of the inlet conduit so as to effect a higher average velocity of the influent water. This influent stream can then be directed to agitate the sediment and divert it upward off of the bottom of the tank. As heated water is drawn out of the bottom of the water heater tank, sediment at the bottom is agitated, diverted upward from the bottom of the tank, and swept out of the outlet conduit with the heated water. Devices employing this method are disclosed in U.S. Pat. No. 4,263,879, issued to Lindahl on Apr. 28, 1981, and U.S. Pat. No. 4,157,077, issued to Lindahl on June 5, 1979.
A problem associated with the continuous removal of sediment from the water heater tank is that the sediment is carried out of the tank into plumbing lines downstream from the tank. This sediment can collect in plumbing, such as solenoids in dishwashers, clothes washer, faucet aerators, shower heads, etc. which can necessitate costly repairs. Another problem associated with the continuous removal of sediment from the water heater, is that the sediment can find its way into the water to be consumed. These particles of sediment, although not harmful, can find their way into or onto hair, dishes, clothes, etc.
The present invention constitutes a sediment flushing apparatus for a water heater tank that seeks to overcome the problems resulting from sediment collection in the bottom of a water heater tank while at the same time providing a simple, easily constructed design that does not adversely affect either the heated water, the downstream equipment, and which is inexpensive to operate and maintain.